As freshmen descend on college campuses, they enter the "red zone" - a period between Labor Day and Thanksgiving during which they are most vulnerable to sexual assault.

This year is different, though. It is the first since the U.S. Department of Education released a list of colleges and universities under federal investigation for their handling of rape and sexual assault complaints, and many schools are making sexual assault awareness programs mandatory for incoming students.

The list, which includes 77 schools under investigation, was released in May. It represents one piece of a national conversation that gained unprecedented political momentum in April, when the newly minted White House Task Force to Prevent Students from Sexual Assault released its first report, alongside a website designed to advise colleges on how to combat rape on campus. Since then, Sen. Claire McCaskill, a Missouri Democrat, has introduced a bill to require annual surveys of students, and require schools to staff confidential advisers on campus.

Oklahoma State University, which is on the list, announced last month that students who do not complete a new 40-minute online course on sexual assault awareness will be barred from registration. Vice President for Student Affairs Lee Bird said the school took the unusual step of asking to be under federal review.

"Sexual violence has been a huge topic for years, but the politics around it and trying to find remedies is what's changed," Bird said, adding that the school offers "hundreds" of alcohol, drug and sexual assault awareness programs throughout the year. "This has been an issue for my 36 years and I imagine it will be an issue on campus for the next 30."

University of California at Berkeley, which is under investigation, has started two new mandatory programs. Freshmen and transfers must attend a sexual awareness program known as Bear Pact, as well as complete an online course, called Haven, about sexual assault, harassment and stalking. The school has also designated a confidential advocate whose role is to assist students who have been sexually assaulted.

While the U.S. Education Department doesn't' release what prompts an investigation, UC Berkeley was the subject of a blistering state audit in June that revealed the school's failure to adequately train resident advisers, athletic coaches and even campus law enforcement on how to handle sexual assault allegations. The audit also found that the administration did not ensure attendance at sexual assault education workshops for freshmen. Based on the school's own data, only 52 percent of the incoming class attended the programs in 2013.

"For us, it's looking at what we need to do to be in federal compliance and follow best practices," said UC Berkeley spokeswoman Janet Gilmore. "It's a continuing effort. We've done a lot, and we know that there's more we can do."

Dartmouth College in New Hampshire, another school under federal investigation, also requires its freshmen to complete Haven. The school adopted a policy in June requiring an independent investigation into sexual assault complaints, and calls for mandatory expulsion for convicted students.

Johns Hopkins University in Baltimore is one of the most recent additions to the list of schools under investigation for possible Title IX violations. It was added Aug. 12.

Title IX is a federal law prohibiting gender discrimination. It regulates institutions' handling of sexual violence and is the same law that guarantees female athletes equal access to sports. Schools that violate Title IX can lose federal funding.

Johns Hopkins is under investigation for its handling of an alleged gang rape of a Towson University student at a fraternity house, Pi Kappa Alpha, in the spring of 2013. Since the allegation became public in May, more Hopkins students have come forward to share their own sexual assault stories, said Laura Dunn, an advocate with nonprofit organization SurvJustice who helped file the initial complaint.

One of those students is a rising junior who asked that her name be withheld. The Associated Press does not identify alleged victims of sexual assault.

In June, she told AP that she was sexually assaulted in 2012 during her first few days on campus. She said her alleged attacker had taken her keys and phone, dragged her into his room and assaulted her.

A few days prior, the student said she had gone to a sexual assault awareness workshop offered to incoming freshmen.

"At the workshop they said anything after you say no is sexual assault. I said to him, 'Don't you remember what we saw yesterday? This is going to be rape.'

"Then he said, 'I didn't go to that stupid thing.' That's when I really got scared."

The workshop she attended, Sex Signals, is on this year's orientation schedule and not labeled as mandatory. Hopkins spokesman Dennis O'Shea said freshmen are required to attend with their resident advisers, and those who do not sign up for it will be registered for a makeup session later in the year.